Yousif said police descended on the mourners and fired tear gas, flash-bang grenades and birdshot.

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The fire ignited after authorities threw flash grenades and tear gas into the apartment to try to flush the shooter out, Stanislaus County Sheriff Adam Christianson told reporters.

CNN: STORY HIGHLIGHTS

Afterwards, police fired tear gas and "flash bang" grenades near the main plaza, where Occupy Wall Street protesters have been camping.

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And those electrons drift up into a gas layer, and when they hit the gas and you get another flash of light.

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But after an anxious 25 minute wait, the flash igniters set up around the leaking gas pipe failed to go off.

CNN: November 21, 2012 -- Updated 1203 GMT (2003 HKT)